I want to get the car ready for all classes, stock or mod , with just a motor and gearing change . Also you are right about the slipping in mod that makes it easier to drive than a gear diff. I could never get my Nikko F1 gear diff to put the power down correctly with any mod motor more powerful than a 10turn brushed, and even then it did not last long . I already have a ton of ball diff hardware . None of my other cars have a gear diff, and I want to keep it that way .